In order to produce the body of such cards, particularly electronic memory cards in accordance with ISO standards, a well known technique consists in making the body of the card by injection moulding, for example of ABS, in a mould whose imprint defines the shape of the body of the card (French Patent No. 2 605 144 describes such a process). Instead of making the body of the card directly by moulding, it is possible to mould a sheet of plastics material from which the bodies of a plurality of cards will subsequently be cut out. However, due to the specifications of dimensions (particularly concerning the thickness of the card body) and of physical properties (particularly concerning the bending properties of the card), it is virtually impossible to make a sheet corresponding to a large number of card bodies.
In both the case of an individual card body and of a sheet corresponding to four card bodies, the piece which is to be printed has relatively small dimensions. Moreover, in view of the fact that the card body has a thickness of the order of 0.8 mm, the bending properties of the piece to be printed are very different from those of the conventional printing supports. For these two reasons, it is delicate to print with the aid of conventional machines, whether offset or screen printing, especially if the graphic symbol is complex by reason in particular of the shades of colour of which it is composed. Moreover, the fact of making upon each passage one single "image" or a limited number of images, is costly and requires, each time, the precise positioning of the piece with respect to the printing machine. In addition, the adhesion of a pre-printed sheet on pieces of reduced dimensions is virtually impossible due to high costs.
It is an object of the present invention to overcome these drawbacks by providing a process for producing card bodies which enables graphic symbols of excellent quality to be produced under acceptable economic conditions, whilst being compatible with the use of an injection-moulding technique.